Well:
1) they are telling what you what goes on with your kid, while he is there.
Most parents do want to know how their kid does, daily.
2) it is mostly negative. Do they tell you anything happy or good about your son? Or that he did?
3) he is 2 years old. Kids this age do not have fully developed impulse-control, NOR do they play interactively. At this age they do what is called "Parallel Play." You can look it up online.
4) at this age, they do NOT know, about social nuances or abstract ways of understanding. They are 'reactors.' They are not fully skilled at social manners. Yet.
5) Teaching a child can be done in negative or positive ways. So, if you do not think they are handling the kids well... you can opt to look for someplace more nurturing.
6) If the teachers are just irked, about normal kid behavior and age related behaviors... then, they are not managing themselves, well. Because, no kid is a robot, nor perfect. Age stages and phases DO occur.
7) is he napping while there? Because, over-tired or over-stimulated kids, get fussy and not at their best.
8) At this age, distraction and redirection works best.
Kids this age have no impulse control.
9) kids when hungry, DO get fussy and moody. AND if they are also tired at the same time, their reactions gets even more pronounced.
A care provider, should know this.
10) what is the kids routines all day? Maybe your son is simply getting over-stimulated? And plus if tired or hungry and him not eating his snacks, well this all creates a fussy child.
Do the kids have any downtime?
11) Again, kids this age do not play interactively. They Parallel Play. They DO get territorial and don't know how to 'share' yet. It is a learning process... not an immediate reaction or mastery. He is 2 years old.
12) Is he teething?
13) telling him to be nice to his friends, sure, mentally they can probably know what you are saying, but it does not mean, they can then do it. Again, expectations has to be in line with per a child's age-stage and development.
14) Toddlers: they have in their minds what they think they can do. But it does not mean they can actually do it. Hence, Toddlers often get frustrated. Their 'emotions' are not even fully-developed yet. They don't even know how to say how they feel, nor the 'names' for their feelings. For a toddler, everything is either good/bad, or happy/frustrating. They don't fully understand the 'gray' or nuances.
At this age, it is all about them being like a rock collecting moss. Not them being fully mastered at all social parameters. Yet.
It is a practice time, and trial and error. That is how they learn.
And it is a time of many mistakes and learning.